1. Field of the Invention
The present invention relates to a lid for pressure-heat cooking vessels such as pressure cookers.
2. Description of the Prior Art
Conventional pressure-heat cooking vessels such as pressure cookers have their lids formed of metal with a specified thickness to give a certain level of pressure resistance. The pressure-heat cooking vessel lids are mainly of two types when classified according to the process of forming: one type is formed by pressing rolled metal plates such as aluminum plates, stainless steel plates and enameled steel plates, and the other type is formed by die-casting aluminum alloys.
During cooking by pressure and heat the lid of the cooking vessel must hermetically seal he interior of the vessel from the outside and thus cannot be opened to visually check the state of the food inside. Also since the conventional lid as well as the vessel body is formed of metal, which is opaque, the food being cooked cannot be seen from outside with the lid closed.